Common American House Spider
Parasteatoda tepidariorum
Theridiidae (Cobweb Spiders), Order Araneae
Physical Description
Bulbous, globular abdomen with a slightly arched back, joined to a smaller cephalothorax. Females are noticeably larger and rounder than males. The body has a smooth to slightly velvety texture with sparse hairs.
Size Estimate
Body length ranges from 5 to 8 mm for females and 3.8 to 6 mm for males, with a leg span of approximately 15 to 25 mm. This appears to be an adult specimen.
Coloration & Markings
Variable coloration ranging from yellowish-brown to dark brown or grey. The abdomen often features darker chevrons, spots, or angular patterns, sometimes with white accents.
Web Type
Irregular tangle web (cobweb) constructed in corners, under eaves, and near structural crevices, featuring sticky vertical lines extending downward to catch crawling prey.
Eye Arrangement
Eight small eyes arranged in two rows of four, typical of the Theridiidae family, with lateral eyes positioned close together or touching.
Leg Characteristics
Long, slender legs with distinct dark and light banding, lacking heavy spination but equipped with a comb of serrated bristles on the tarsus of the fourth pair for wrapping prey.
Venom & Safety Information
Venom Information
Neurotoxic venom specialized for subduing small insect prey; has low potency regarding humans and is generally not considered medically significant.
Medical Significance
Harmless to humans; bites are extremely rare and typically only occur if the spider is directly pressed against the skin. Symptoms are minor and usually limited to localized mild pain or redness.
Safety Recommendations
No special precautions needed beyond normal caution; can be gently relocated outside using a cup and paper if found in an unwanted location.
Habitat & Behavior
Habitat & Range
Cosmopolitan distribution worldwide; frequently found in and around human habitations, basements, sheds, outbuildings, eaves, and occasionally sheltered outdoor vegetation.
Behavior & Temperament
Non-aggressive and timid; hangs upside down in its web and typically retreats or drops to the ground when disturbed.
Diet & Prey
Feeds on a wide variety of household and garden insects, including flies, mosquitoes, ants, beetles, and other spiders, capturing them via sticky web threads.
Seasonal Activity
Active year-round indoors, with peak outdoor visibility and reproductive activity occurring during the warmer spring and summer months.
Description
The Common American House Spider is an inconspicuous yet beneficial neighbor found in homes and buildings globally. Recognized by its bulbous abdomen and tangled web, it quietly helps control household insect populations without posing any threat to humans.
Key Features
Bulbous, high-domed abdomen, irregular cobweb structure, banded legs, and a preference for building webs in structural corners and under eaves.
Similar Species
Steatoda grossa (False Black Widow) and Latrodectus species (Black Widows); distinguished by lacking the glossy black body and red hourglass marking of widow spiders and possessing more pronounced patterning.
Life Cycle
Females produce several brownish, pear-shaped papery egg sacs containing up to several hundred eggs each. Spiderlings disperse via ballooning after hatching, undergoing multiple molts to reach maturity within a year.
Ecological Importance
Acts as an effective natural pest controller by reducing populations of nuisance insects like flies and mosquitoes around human habitations.
Conservation Status
Not evaluated by the IUCN, but highly abundant, widespread, and stable globally with no major threats.
Interesting Facts
Females can live for several years and may produce multiple egg sacs from a single mating event. They are remarkably resilient urban dwellers that thrive alongside human development.
Photography Tips
Photograph from the side or slightly above to capture abdominal patterns and web placement. Use macro lenses with good lighting while avoiding sudden vibrations that cause the spider to retreat.
Identified: 2026-08-31T23:41:25.379358